Protecting device for electric detonators



Nov. 9 1926. 1,606,419

H. L. GRANT PROTECTING DEVICE FOR ELECTRIC DETONATORS Filed Nov. 20. 1925 flarry Grant, w, My

attorney,

Patented Nov. 9, 1926.

PATENT, OFFICE.

HARRY L. GRANT, OF TAMAQUA, PENNSYLVANIA, ASSIGNOR TO ATLAS POWDER COMPANY, OF WILMINGTON,'IDELAWARE, A CORPORATION OF DELAWARE.

' PROTECTING nnvicn FOR nnnc'rnrc nn'rormzrons.

Application filed November This invention relates to. a protecting de vice for electric detonators of the character of that shown in my copending application, Serial No, 7 48,214, filed on November 6, 1924.

Like the device of the application referred to, the protecting device of thepresent invention is intended to be appliedto the leadin wires of electric detonators and to serve, while in position, to establish a short circuit 10 between the two lead in wires, so that any stray currents imposed upon the lead-in wires, outwardly of the point of application of said device, may not find their way to the detonator and prematurely explode the same and so that no difference 111 potential can be created between the lead wires inwardly of the point of application of the device, under the influence of accidental or stray currents imposed upon said wires, under any conditions.

I am aware-of the fact that it has been proposed to short circuit. the main firingcable leading from' the blasting machine. However, that method is of utility only at the time of use. An important object of the present invention is to provide a structure which will be operative with respect to the individual detonators, at all times between the time of manufacture of the detonator and until the sameis actually exploded on the job, the structure being of particular utility during the time that the detonator is being transported and while it is being handled about the work preliminary to the actual connection of its lead wires to the main firin cable. The present application is directed to the protection of a specific form of short circuiting shunt and method ofapplying the same to the lead-in wires of the individual blasting caps,preferably with its inner end Fig. 1 is a perspective-view of one form of shunt before its apphcation to the lead wires of the detonator,

20,-1925. Serial No. 70,370.

Fig. 2 is a side elevation of the detonator with the shunt of Fig. 1 applied-thereto,

Fig. 3 is a cross sectional View through the shunt of Fig. 2,

Fig. 4 is a perspectiveview of a slightly modified form of shunt,

Fig. 5 is a side view of a detonator having the shuntof Fig. 4 applied thereto, and

Fig. 6 is a cross sectional view of the shunt of Fig. 5.

Like numerals designate corresponding parts in all of the figures of the drawing.

Referring to the drawing, 5 desi conventional electric detonator an 6 and 7 designate the usual lead-in wires of said detonator.

In the ordinary use of the detonator t-heflow of current of sufiicient strength past an igniting element 8, which connects the inner ends of the wires 6 and 7, explodes the detonator. The lead-in wires are insulated, as indicated at 9 and 10, for some distance from the detonator and the ends-of the lead-in wires are left bare beyond the point where the insulation terminates, to adaptthem for ready application to the firing cable, leading from a blasting machine.

" In the form of the invention-illustrated in and passed throu h the shunt 6r clip of- Fig. 1; after whic the ends of the clip' are folded down upon the body portion thereof, as illustrated in Fig. 3, in such manner as to have firm engagement with and uponthe lead wires and preferably with one side ofthe shunt abutting firmly: against the .ter- .ininal ends of the insulation of the lead ates the 7 Figs. 1, 2 and 3, the shunt consists of a merewires. Thisarrangement provides a double safeguard by holding the lead wires of the detonator into contact with each other, at "two separate and distinct points. In addition, it directs the terminal ends of the lead wires rearwardly and beneath the insulated portions of the lead wires where they will be more protected from chance contact with str'ay current carrying objects than would be the case if the ends were left free. e

'Theform of the inventionv illustrated in be apparent from an inspection of Fig. 6,

where it will be seen that the ends 12 are bent down over the lead wires. At this time, the body portion 11 forms an electrical connection between the bared portions of the lead wires and the shunt abuts the outer ends of the insulation upon said lead wires. Since the insulation protects the lead wires from the shunt, inwardly, to the detonator and since the shunt itself short circuits any stray currents imposed upon the lead wires, outwardly ofits point of application, it is clear that the shunt will act as a protector as long as it-is in place. It is not to be understood that the device is of utility only when actually touchin the termination of the insulation. It wil give a very appreciable measure of protection even when spaced somewhat from the insulation because the influences which might bring about such difference in potential between the lead wires as to explode the detonator,

are not those sought to be created by an intelligent human agency but only those which might accidentally occur. Stray currents of such low E. M. F. as to escape ordinary notice constitute a marked source of danger and are rendered absolutely harmless by this invention.

It is to be understood that the invention is not limited to the precise construction set forth but that it includes within'its purview whatever changes fairly come within' either tlie terms or the spirit of the appended c aims. I

\ wires.

neoaaie 1. The herein described method of aptplying a shunt to the lead wires of an'electric detonator, which consists of bending the terminal ends of a metallic strip into engagement with said lead wires, with the metallic strip positioned directly against the terminal ends of the insulation of the lead 2; The herein described method of applying a shunt to the lead wires of an electric detonator, which consists of bending one end of a metallic strip over both of the lead wires and bending the other end of said strip over both of said lead wires at another point said lead wires being given a return bend between said points and the shunt becidentally imposed or stray currents and having its opposite ends bent into engagement with said lead wires.

4. A structure as recited in claim 3, wherein both of the lead wires pass through each end of the shunt, said wires being given a return bend between their points of passage through the shunt.

In testimony whereof he affixes his signature.

HARRY L. GRANT. 

